<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Upload Test</title>
</head>
<body>
    <div>
        <input type="file" name="file" onchange="uploadFile(this);">
    </div>
    <div>
        <pre id="ret-content"></pre>
    </div>
</body>
<script>
    function uploadFile(t){
        if (t.files.length <= 0 )return;

        let fm = new FormData();

        fm.append('file',t.files[0]);

        fetch('/data',{
            method:'POST',
            body:fm
        })
        .then(
            async res => {
                if(res.ok){
                    return res.text();
                }
                throw new Error(`${res.status} ${statusText}`)
            }
        )
        .then(text => {
            let d = document.getElementById('ret-content');
            d.innerHTML = 
            `<img src="${text}" style="width:80%;height:auto;">`;
        })
        .catch(err => {
            console.error(err.message);
        });
    }
</script>
</html>